脉冲爆轰发动机的系统性能分析

采用简化的脉冲爆轰推进装置模型，利用热循环效率分析方法，推导了包含进气道总压恢复系数的热循环效率公式. 并在特定来流条件下，考察了一个爆轰循环中进气道总压恢复系数和燃烧室初始温度对热循环效率和比冲的影响. 研究发现，降低来流总压损失有助于提高热循环效率，而提高燃烧室初始温度能更有效地提高热循环效率. 据此，提出了多级重起爆脉冲爆轰发动机概念，利用在突扩截面上解耦的爆轰波的前导激波去再次压缩工质，进一步提高工质的热力学参数，从而提高脉冲爆轰装置的热循环效率. 推导了此种构型PDE的热循环效率计算公式，并对多级重起爆脉冲爆轰发动机进行了原理性论证. 研究结果表明，多级重起爆方法提高了燃烧室的爆前温度，从而有效地提高脉冲爆轰发动机热循环效率. 最后，关于出口工质的非完全膨胀的情况，做了定性的阐述，认为只有降低工质的出口压力，才能更有效增加工质的出口动能，从而提高热循环效率. 

SYSTEM PERFORMANCE ANALYSIS OF PULSE DETONATION ENGINES

A simplified model of Pulse Deotonation Engines(PDEs) isadopted in present paper to estimate the system performance withthermodynamic cycle analysis method. The analytical expression of PDE'sthermodynamic cycle efficiency is derived in relation to the parameter oftotal pressure recovery coefficient. In addition, we attempt to investigatethe influence of the total pressure recovery coefficient of PDE inlets andinitial temperature of combustion chamber on the PDE thermodynamic cycleefficiency. The results demonstrates that, reducing total pressure loss ofthe inlets is beneficial to increase the thermodynamic cycle efficiency, andincreasing the initial temperature of combustion chamber can even apparentlyenhance thermal efficiency. Based on the current results, Multistage PulseRe-Detonation Engines(MPRDEs) configuration is presented in this paper forthe first time. We use the shockwave front of detonation waves decoupled atcorner to compress the working medium, which improves the thermodynamicalparameters of the working medium and PDE's system performance. Thethermodynamic cycle efficiency of this configuration is derived, whichdemonstrates the possibility of MPRDE configuration theoretically. Theresult shows that, MPRDE configuration can improve the thermal efficiencyeffectively via raising working medium's temperature in front of detonationwave. Finally, because some of the working medium is not perfectly expandedwhen rushing out of nozzle, a qualitative discussing is carried out on PDE'sthermal efficiency under different exit pressures. The moment of workingmedium will be promoted and thermal efficiency will be improved when theexit pressure is lowered.